In a magnetic recording disk drive, data is written by thin film magnetic transducers called “heads”, which are supported over a surface of the disk while it is rotated at a high speed. The heads are supported by a thin cushion of air (an “air bearing”) produced by the disk's high rotational speed.
FIG. 1 illustrates a prior art MR head, which may be employed as a magnetic head on a slider. The head 30B has a pole tip region, an insulation stack region and a coil region, the pole tip region extending from the ABS to the insulation stack region, the insulation stack region extending from the pole tip region to the back gap (not shown) and the coil region located in the insulation stack region but spaced from the pole tip region. In the present framework, the first and second shield layers S1 and S2 are located in the pole tip region for the protection of the MR sensor. The first shield S1 terminates between the pole tip region and the coil region along a slope 50. This provides a sunken or depressed area 51 for subsequent thin film layers of the head which makeup the insulation stack. The second gap layer G2 extends along the slope 50 of the first shield S1, thence perpendicular to the ABS toward a back region of the head. It should be noted that leads are not shown following the same path. The leads for the head 30B may take a different path.
The layer S2/P1, write gap, insulation layer I1, write coil, insulation layers I2 and I3, and the second pole piece P2 are all recessed by the depression provided by the first shield layer S1 in the insulation stack region lowering the height of the second pole piece above the write gap plane so as to enhance planarization of the second pole tip PT2. This significantly reduces the aspect ratio of the resist during fabrication of the pole tip PT2, enabling construction of the pole tip at the ABS with a thin layer of resist, in the order of 4 um as seen by the thickness of the resist layer 40 at the ABS. A thinner resist layer permits a narrower pole tip to be precisely constructed with good definition, thereby enhancing the bit density of the head. Of further significance, is elimination of a large portion of the first shield layer S1, which reduces the induction that opposes the operation of the write coil. The portion of the first shield layer S1 remaining is remote from the write coil so that when high frequency currents are conducted through the write coil, its EMF is not significantly opposed by the CEMF of the first shield S1.
The slope 50 of the first shield S1 may be constructed by a resist layer with a negative slope 52. Permalloy may then be plated adjacent the negative slope, after which the resist is removed to produce the slope 50 of the first shield S1.
Prior art FIG. 2A illustrates a top view of the MR head of FIG. 1. As shown, an end 201 of the top pole layer P2 extends farther toward the coil 202 with respect to the flanking portions of the bottom pole layer P1. In use, a photoresist layer that is deposited over the coil 202 for creating the notched pole tip PT1b adhesively couples to the end 201 of the top pole layer P2. However, it fails to reach ends 203 of the bottom pole layer P1. This results in the exposure of the coil 202 during ion beam milling that is used to create the notched pole tip PT1b. 
Prior art FIG. 2B is a cross-sectional view taken along line 2B—2B of FIG. 2A which illustrates the manner in which the ion beams 200 erode the coil 202 during the processing of the structure of FIG. 1. As shown, a primary contributor of this problem is the fact that it is extremely difficult to mask a photoresist layer tightly against an edge of the bottom pole layer P1.
Prior art FIG. 2C illustrates actual damage 204 to the coil structure 202 resulting from the above problem. It should be further noted that since the coil structure 202 is closer and tighter to the bottom pole P1, any damage to the coil structure 202 has significant ramifications on data rates and overwriting operations.
There is thus a need for a magnetic head structure and a method of manufacturing the same that avoids damage to a coil structure during ion beam formation of a notched pole tip.